TRANSFORMATION OF ORGANIC MATTER 685 



It was suggested 34 that C0 2 formation in soil, whether treated with 

 organic matter or not, does not proceed in accordance with the growth 

 law of bacteria. Under aerobic and constant environmental conditions, 

 it proceeds in accordance with the equation 



x = ak t m 



in which x is the quantity of C0 2 produced in time t, a is the initial 

 CO2 content of the soil, and k and m are constants. However, as experi- 

 ments with peat and other soils have shown, the CO2 formation in 

 the soil is not always necessarily parallel to the concentration of carbon. 



As to the method used for measuring the evolution of carbon 

 dioxide, at first the air freed from C0 2 was passed through the soil 

 placed in a container, and the C0 2 in the outgoing air measured. 35 

 This method was later modified so that air, previously feed from C0 2 , 

 was passed continuously over the surface of the soil in containers. 

 Under these conditions the soil more nearly approaches normal, since 

 constant aeration greatly accelerates microbiological activities. 36 



Formation of ammonia {and nitrate) as an index of decomposition of 

 organic matter in the soil. Nitrogen is present in the complex organic 

 substances largely in the form of proteins. In the process of decom- 

 position, these are first hydrolized to proteoses, peptones and poly- 



34 Lemmermann, O., and Weissmann, H. Z. Pflanzenernahr. u. Dung., 2B: 

 387-395. 1924. 



35 Pettenkofer, M. Ueber eine Methode die Kohlensaure in der atmosphar- 

 ischen Luft zu bestimmen. Chern. Soc. Trans., 10: 292. 1858; Peterson, P. 

 Ueber den Einfluss des Mergels auf die Bildung von Kohlensaure und Salpeter- 

 saure im Ackerboden. Landw. Vers. Sta., 13: 155-175. 1870; Wollny, 1897 (p. 

 477); Stoklasa and Ernest, 1905 (p. 34); Lemmermann, K., Fischer, H., and 

 Fresenius, L. Untersuchungen liber die Zersetzung der Kohlenstoffverbindungen 

 verschiedener organischer Substanzen im Boden, speciell unter dem Einfluss 

 von Kalk. Landw. Jahrb., 41: 217-256. 1911; Klein, M. A. Studies in the 

 drying of soils. Jour. Amer. Soc. Agr., 7: 49. 1915; Gainey, P. L. Parallel 

 formation of carbon dioxide, ammonia and nitrate in the soil. Soil Sci., 7: 

 293-311. 1919. 



36 Fred, E. B., and Hart, E. B. The comparative effect of phosphates and 

 sulfates on soil bacteria. Wis. Agr. Exp. Sta. Res. Bui. 35. 1915; Fraps, G. S. 

 Oxidation of organic matter in soils. Texas Agr. Exp. Sta. Bui. 181. 1915; 

 Potter, R. S., and Snyder, R. S. Carbon dioxide production in soils and carbon 

 and nitrogen changes in soil variously treated. Iowa Agr. Exp. Sta. Res. Bui. 39. 

 1916; Merkle, F. G. The decomposition of organic matter in soils. Jour. Amer. 

 Soc. Agron., 10: 281-302. 1918; Keller, J. R. Studies on the correlation be- 

 tween the production of COo and the accumulation of ammonia by soil organ- 

 isms. Soil Sci., 5: 225-239. 1918; Waksman and Starkey, 1923 (p. 739). 



